And I love it. Have been using it for some time
There are SOGo extensions for thunderbird and Lightning for native calendar and address books. I do not know of a native solution for integration with Outlook

And I love it. Have been using it for some time
There are SOGo extensions for thunderbird and Lightning for native calendar and address books. I do not know of a native solution for integration with Outlook

We use web, like sensible people. Fat mail clients are generally a pretty awful idea.

I think that the idea of using mail clients is mostly something from the Exchange world because Exchange lacked a good interface for so long. Outside of Exchange users, I rare find anyone who would even think to try out a fat mail application.

Even when we were on Office 365, we didn't use Outlook. Literally the worst thing that ever happened to email. Outlook is truly awful. OWA is better, still not great. But way easier to manage, and more reliable.

We ran on Zimbra for mail years, then tried Rackspace and O365, but returned to Zimbra. Zimbra is solid and pretty easy to use and "just works". It's got a lot of features. Biggest complaint is that they used to be the absolute leader in email GUIs, now they are trailing terribly having not updated for around a dozen years.

Last year they promised a major new update, then silently dropped it. So a lot of people are losing faith in where they are headed.

No one makes a single thing like that. But putting your own together is not a big deal. We use Zimbra, NextCloud, and Collabora. It all integrates and gives you storage like OneDrive, email like Exchange, word processing, spreadsheet, and presentation software.

Yup, we've been using that all in production for a while (Collabora is the only recent part.) Collabora takes LibreOffice and makes it hosted in your web browser so that it launches right from inside of your NextCloud storage.